Originally Posted by will76

if you really want to do the right thing and give him an honest, mature response I would tell him this.

Hey, I really enjoy hanging out with you and like being friends but some of my other friends who come over to my house have been known from time to time to smoke weed. I wouldn't want to put you into a situation where you could potentially be around people doing that and it affect your job or get you in any kind of trouble. (reword that into your own words with the same point). See how he responds, he will either say " thanks for thinking of me " and he will stop asking to hang out with you at your house with the other people there or " its ok just tell them to not do it in front of me" or " Im going to raid your house next time you have a party It will likely be one of the first two .